Who can explain the MG1 Logic

[whittlebeast]

I am trying to find someone that knows the tuning logic of the MG1 ECU. This is the first 4 sec of a typical hole shot. The top trace has the basic four sensors plus a WOT timer.

The second graph down shows the VE lookup and the resulting AFR. Since AFR is relatively stable, there is no ignition cut active.

Graph 3 indicated there must be a table that is leaning on the spark timing. Desired load and Engine Load are in perfect since indicating Desired Load is a primary control. Torque Request is near 100%, but 100% of what?

Graph 4 has the TPS, as measured at the throttle body, so clearly the torque is being pulled back, making me question the Torque Request comment above.

Who knows and understands how all of these torque limiters tables are controlling this sequence of events. Once the logic is documented, the tuning by tuning companies can begin. Until this happens, it appears tuners are simply guessing.

All of this data is collected with HPTuners and graphed with MegaLogViewer HD.

[whittlebeast]

It looks like the real question it how does the ECU go from the minimum of all of the torque limiters and convert it to Desired Load? Does the ECU then PID to a TPS to converge Desired Load and Engine Load?

[whittlebeast]

This is what Grok claims.

Calculating the **Desired Load** in Bosch ECU tuning, particularly for Motronic systems like ME7, MED9, or MED17, involves understanding the ECU's torque-based control strategy. The Desired Load (often referred to as engine load or relative cylinder fill) is a critical parameter that determines how much air the engine should aspire to achieve the requested torque, which ultimately influences boost, fueling, and ignition timing. Below is an explanation of how Desired Load is typically calculated, based on the principles used in Bosch ECUs:

### 1. **Torque Request as the Starting Point**
- Bosch ECUs operate on a **torque-based control system**, where the driver's input (via the accelerator pedal) is interpreted as a torque request.
- The **Driver Requested Torque** is derived from **pedal maps** (e.g., pedal position vs. engine speed). These maps translate the accelerator pedal position into a desired torque value, often expressed as a percentage of maximum torque or in Nm (Newton-meters).
- For example, in the EcuTek tuning documentation for the VW AG EA855 engine, the pedal maps output a torque request, which is then multiplied by the **Maximum Indicated Torque Maps** for the specific vehicle region, gear, and operating mode (e.g., valve lift).[](https://ecutek.atlassian.net/wiki/sp...ngine%2BTuning)

### 2. **Conversion to Desired Load**
- The ECU translates the torque request into a **Desired Load** (or relative cylinder fill) by using tables such as the **Reference Air Charge** table or **KFMIRL** (Engine Load Desired) in Bosch ME7 systems.
- **Desired Load** is typically expressed as a percentage (%) or in terms of air mass (e.g., mg/stroke). It represents the amount of air the engine needs to achieve the requested torque.
- The ECU uses the **Reference Air Charge** table, indexed by parameters like engine speed, valve lift, and camshaft position, to determine the air mass required. This air mass is then converted into a load value using engine displacement and other calibration factors.[](https://ecutek.atlassian.net/wiki/sp...ngine%2BTuning)

- **Formula for Load (Simplified)**:
In some Bosch systems, load can be approximated using the relationship between air mass flow and engine parameters. For example, a simplified formula from older Bosch systems (like Ford EEC) is:
\[
\text{Load} = \frac{(\text{MAF reading in lbs/min} \times 2)}{(\text{RPM} \times \text{Number of Cylinders})} \div \text{Engine Displacement}
\]
However, in modern Bosch ECUs, the load is calculated internally using more complex models that account for volumetric efficiency, intake air temperature (IAT), and manifold pressure. The ECU uses a **volumetric efficiency map** or **nominal charge map** to refine this calculation.[](https://eectuning.org/forums/viewtopic.php?t=13803)[](https://oldskulltuning.com/moto-mori...-bosch-mse6-0/)

### 3. **Key Maps Involved**
Several maps in the ECU influence the Desired Load calculation:
- **KFMIRL (Engine Load Desired)**: This map defines the desired load based on torque request and engine speed. It?s often inversely related to **KFMIOP** (Map for Optimum Engine Torque), which caps the maximum achievable load.[](https://www.hpacademy.com/forum/gene...-in-bosch-me7/)[](https://blog.uobdii.com/motronic-ecu...ps-and-guides/)
- **LDRXN (Maximum Boost Allowed)**: This map sets the upper limit for load (and thus boost) across the RPM range. For example, in Bosch ME7, boost in mbar can be approximated as:
\[
\text{Boost (mbar)} = (\text{Load} \times 10) + 300 - 1000
\]
So, a load of 160% corresponds to approximately 0.9 bar of boost.[](https://www.hpacademy.com/forum/gene...-in-bosch-me7/)
- **Reference Air Charge Tables**: These tables (indexed by port flaps, valve lift, or cam positions) determine the air mass (mg/stroke) needed for a given torque output. This air mass is used to calculate manifold pressure and boost targets.[](https://ecutek.atlassian.net/wiki/sp...ngine%2BTuning)
- **IAT Correction Maps**: Intake air temperature affects air density, so the ECU adjusts the desired load to compensate for temperature variations.[](https://blog.uobdii.com/motronic-ecu...ps-and-guides/)

### 4. **Boost and Throttle Control**
- Once the Desired Load is calculated, the ECU uses it to determine the **boost setpoint** (for turbocharged engines) or **throttle angle** (for naturally aspirated engines).
- In turbocharged systems (e.g., Bosch MED17), the ECU calculates the required manifold pressure to achieve the desired air charge. This involves the **Boost Setpoint Offset Table** and **Pressure Upstream Turbo Limits**, which ensure the turbo delivers the necessary pressure.[](https://ecutek.atlassian.net/wiki/sp...ngine%2BTuning)[](https://www.hpacademy.com/forum/wino...l-bosch-med17/)
- The ECU may also adjust the wastegate duty cycle or throttle position to achieve the target load, especially in systems like the Bosch MED17.9.63, where boost targets are derived from relative cylinder fill rather than direct pressure targets.[](https://www.hpacademy.com/forum/wino...l-bosch-med17/)

### 5. **Practical Considerations in Tuning**
- **Tuning Desired Load**: To increase performance, tuners often modify the **KFMIRL** or **Reference Air Charge** tables to request higher load values, which results in increased boost or throttle opening. However, this must be balanced with other parameters like ignition timing, fuel delivery, and knock control to avoid engine damage.[](https://www.hpacademy.com/blog/how-t...tuning-course/)[](https://www.hpacademy.com/forum/gene...-in-bosch-me7/)
- **MAF Scaling**: The Mass Air Flow (MAF) sensor calibration must be accurate, as it directly affects load calculations. Incorrect MAF scaling can lead to improper load values, impacting performance and drivability.[](https://www.hpacademy.com/blog/how-t...tuning-course/)[](https://www.reddit.com/r/ECU_Tuning/..._motronic_ecu/)
- **Checksums and Software**: Tools like WinOLS, TunerPro, or EcuTek are used to modify these maps. Tuners must ensure checksum corrections are applied to prevent ECU errors.[](https://www.hpacademy.com/blog/how-t...tuning-course/)[](https://www.vwvortex.com/threads/ong...-1-8t.5496661/)
- **Risks**: Increasing Desired Load beyond the engine?s mechanical limits or without proper tuning of related parameters (e.g., ignition, fuel, or boost limiters) can lead to engine knock, overheating, or component failure. Tuning should be done on a dyno by trained professionals.[](https://ecutek.atlassian.net/wiki/sp...ngine%2BTuning)[](https://www.caracaltech.com/articles...25529176db54c1)

### Summary
In Bosch ECU tuning, Desired Load is calculated by:
1. Interpreting the driver?s pedal input as a torque request via pedal maps.
2. Converting the torque request into a desired air charge (load) using tables like KFMIRL or Reference Air Charge, adjusted for engine speed, valve lift, and cam positions.
3. Using volumetric efficiency and MAF data to refine the load calculation.
4. Adjusting boost or throttle to achieve the target load, with limits set by maps like LDRXN.

For precise tuning, you?ll need to use software like WinOLS, ECM Titanium, or EcuTek to modify these maps, ensuring all related parameters (fuel, ignition, boost) are adjusted accordingly. Always verify changes on a dyno and ensure the engine is in good health before tuning.[](https://www.hpacademy.com/blog/how-t...tuning-course/)[](https://ecutek.atlassian.net/wiki/sp...ngine%2BTuning)[](https://www.hpacademy.com/forum/gene...-in-bosch-me7/)

If you have a specific Bosch ECU model (e.g., ME7, MED9, MED17) or vehicle, let me know, and I can provide more tailored guidance!

[whittlebeast]

More specific to BRP

Calculating **Desired Load** in the Bosch MG1 ECU as used by BRP (Bombardier Recreational Products), such as in Can-Am vehicles with the MG1CA920 or similar ECUs, follows a similar torque-based control strategy as other Bosch ECUs (e.g., ME7, MED17), but with specifics tailored to BRP?s applications, such as turbocharged Rotax engines (e.g., Maverick X3 Turbo). The MG1 ECU is a modern, petrol-focused controller with advanced security features, introduced around 2016, and is used in high-performance recreational vehicles. Below is an explanation of how Desired Load is calculated in this context, incorporating insights from the provided web results and general Bosch tuning principles.

### 1. **Torque Request as the Starting Point**
- The Bosch MG1 ECU in BRP vehicles uses a **torque-based control system**, where the driver?s input (via the throttle pedal or mode selector, e.g., Eco or Sport) is interpreted as a torque request.
- **Pedal Maps**: The accelerator pedal position is mapped to a torque demand, typically via tables that vary by driving mode (Eco, Sport, etc.) and engine speed (RPM). For example, in the Can-Am Maverick X3 with the MG1CA920 ECU, the **Desired Throttle Angle ? Eco** and **Desired Throttle Angle ? Sport** maps define throttle response, which indirectly influences torque demand.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- These maps output a requested torque value, often expressed as a percentage of maximum torque or in Nm, based on pedal position, RPM, and vehicle mode.

### 2. **Conversion to Desired Load**
- The torque request is translated into **Desired Load** (or relative cylinder fill), which represents the air mass required to achieve the requested torque. This is typically expressed as a percentage (%) or in mg/stroke.
- **Key Maps Involved**:
- **Map for Calculation of Nominal Charge**: This map, referenced in tuning resources for BRP?s MG1CA920, calculates the nominal air charge (air mass) needed based on manifold pressure, RPM, and other factors like throttle position.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- **Relative Mass Flow Over Throttle Valve**: This map adjusts the air mass calculation based on throttle valve position, ensuring the ECU accounts for actual airflow.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- **Relative Fresh Air as Function of Manifold Pressure**: This map correlates manifold pressure to the relative air charge, refining the load calculation for turbocharged engines.[](https://oldskulltuning.com/can-am-me...tunerpro-maps/)
- The ECU uses a **volumetric efficiency model** (calibrated for the Rotax engine?s displacement and turbo setup) to convert the torque request into a target air mass. This involves factors like:
- Engine displacement (e.g., 900cc for the Maverick X3 Turbo).
- Intake air temperature (IAT) and manifold absolute pressure (MAP) sensor readings.
- Turbo boost pressure, which is critical for BRP?s turbocharged engines.

- **Simplified Load Calculation**:
While exact formulas vary, the Desired Load can be approximated as:
\[
\text{Load} (\%) = \frac{\text{Air Mass (mg/stroke)}}{\text{Maximum Theoretical Air Mass}} \times 100
\]
The air mass is derived from MAF (Mass Air Flow) sensor data or calculated using MAP, IAT, and volumetric efficiency tables. For turbocharged BRP engines, the ECU adjusts this based on boost pressure targets.

### 3. **Boost and Throttle Control**
- In BRP?s turbocharged applications, the Desired Load directly influences **boost pressure targets**. The ECU uses maps like:
- **Wastegate for Boost Linearization**: Adjusts wastegate position to achieve the target boost pressure, ensuring the desired air charge.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- **Boost Pressure Limiter by Atmospheric Pressure**: Caps boost to prevent overboost, especially at varying altitudes.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- **Boost Pressure**: Defines the target manifold pressure needed for the Desired Load.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- For example, in the Can-Am Maverick X3, a Desired Load of 160% might correspond to a boost pressure of approximately 0.9 bar, calculated as:
\[
\text{Boost (mbar)} = (\text{Load} \times 10) + 300 - 1000
\]
This is a rough approximation and varies with MG1-specific calibrations.[](https://oldskulltuning.com/can-am-me...tunerpro-maps/)
- The throttle valve is also controlled to regulate airflow, using maps like **Desired Throttle Angle** (Eco/Sport), which adjust based on the torque request and operating mode.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)

### 4. **Specifics for BRP MG1 ECU**
- **ECU Type**: BRP vehicles, like the Can-Am Maverick X3 (model year 2021+), often use the **MG1CA920** ECU, which is a petrol-specific Bosch MG1 variant with enhanced security features (e.g., bench protection introduced in mid-2020).[](https://www.tuningtools.com/bitbox-b...1-bench-module)[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- **Tuning Challenges**: The MG1 ECU in BRP applications has been noted for its encryption, making tuning difficult without specialized tools like BitBox or bFlash. Some MG1 ECUs (e.g., post-2020) require unlocking before maps can be modified.[](https://www.maicsonecutuning.com/blo...-ecu-unlocking)[](https://bitsoftware.com/bitbox/catalog/58)
- **Available Maps**: Tuning software like TunerPro for the MG1CA920 provides access to maps critical for Desired Load calculation, including:
- Air calculation: Relative mass flow, nominal charge, and manifold pressure-based air charge.
- Boost control: Wastegate and boost pressure limiters.
- Throttle control: Desired throttle angles for different modes.
These maps are used to adjust the Desired Load to increase performance (e.g., Stage 1 tuning yields +15hp/+15Nm on the Maverick X3 Turbo).[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)

### 5. **Practical Tuning Considerations**
- **Modifying Desired Load**: Tuners increase Desired Load by adjusting the **Nominal Charge Map** or **Boost Pressure Target** to request more air mass, resulting in higher boost and power. However, this requires corresponding adjustments to:
- Fueling: Maps like **Maximum Desired Air-Fuel Ratio** and **Lambda Efficiency** ensure proper air-fuel ratios.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- Ignition: **Spark Advance** maps must be optimized to prevent knock.
- Boost Limits: **Boost Pressure Limiter** and **Wastegate** maps must be raised to allow higher boost.
- **Tools**: Software like TunerPro, BitEdit, or bFlash is used to access these maps. For BRP?s MG1CA920, TunerPro XDF files cost around ?80 and provide detailed map definitions.[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)
- **Risks**: Overincreasing Desired Load without proper tuning can lead to overboost, knock, or engine damage, especially in turbocharged Rotax engines. Dyno tuning by professionals is recommended.
- **MAF/MAP Calibration**: Accurate MAF or MAP sensor calibration is critical, as these directly affect load calculations. Incorrect scaling can cause drivability issues or power loss.

### Summary
In the Bosch MG1 ECU (e.g., MG1CA920) used by BRP:
1. The **torque request** is derived from pedal maps (e.g., Desired Throttle Angle ? Eco/Sport) based on driver input and mode.
2. The torque request is converted to **Desired Load** using maps like **Nominal Charge**, **Relative Mass Flow**, and **Manifold Pressure-Based Air Charge**, adjusted for volumetric efficiency and turbo boost.
3. **Boost pressure** and **throttle angle** are controlled to achieve the target load, using maps like **Wastegate for Boost Linearization** and **Boost Pressure Limiter**.
4. Tuning involves modifying these maps to increase Desired Load for more power, but requires careful adjustment of fueling, ignition, and boost limits.

For BRP-specific tuning, tools like TunerPro with XDF files for the MG1CA920 are recommended, but post-2020 ECUs may require unlocking due to enhanced security. Always verify changes on a dyno and ensure the engine and turbo are in good condition.[](https://www.maicsonecutuning.com/blo...-ecu-unlocking)[](https://oldskulltuning.com/can-am-ma...tunerpro-maps/)

If you have a specific BRP model, ECU variant, or tuning goal, let me know for more tailored advice!

[whittlebeast]

Here is a sample data log as collected by HPTuners and graphed with MegaLogViewer HD. On the two bottom traces, you can see the correlation between the channels.

[JT_alex]

I am trying to find someone that knows the tuning logic of the MG1 ECU. This is the first 4 sec of a typical hole shot. The top trace has the basic four sensors plus a WOT timer.

The second graph down shows the VE lookup and the resulting AFR. Since AFR is relatively stable, there is no ignition cut active.

Graph 3 indicated there must be a table that is leaning on the spark timing. Desired load and Engine Load are in perfect since indicating Desired Load is a primary control. Torque Request is near 100%, but 100% of what?

Graph 4 has the TPS, as measured at the throttle body, so clearly the torque is being pulled back, making me question the Torque Request comment above.

Who knows and understands how all of these torque limiters tables are controlling this sequence of events. Once the logic is documented, the tuning by tuning companies can begin. Until this happens, it appears tuners are simply guessing.

All of this data is collected with HPTuners and graphed with MegaLogViewer HD.

it sound like we have the same problem , WOT!!!

[whittlebeast]

I have no idea if people are using other software to modify limiters to open additional tables, compared to what I am seeing in HPTuners.

[activejetsport]

Good info!

[whittlebeast]

I think I nailed the tune. It gets full throttle all the way up to 8400 RPM. AFR looks great. Timing is totally stock by design. I have been 93 fuel, but you never know when 91 may be the only choice. Right now, I am showing 80 on the dash with over 1/2 tank of fuel, 200 LB rider and not trimmed all the way up. The ski is totally stock.